A connection structure in which a connecting pin is passed through a connection hole formed in a pedal arm and the connecting pin is retained by a retaining member, so that a prescribed connecting member is connected to the pedal arm via the connecting pin is widely used in connecting a clevis or the like to, for example, the pedal arm of a vehicle operation pedal. Connection structures described in Patent Documents 1 to 3 are examples of the above-described connection structure. A clip that is engaged with a head portion of a connecting pin is used as a retaining member in each of Patent Documents 1, 2, and a β-clip that is fitted to a distal end portion of a connecting pin that protrudes from a connection hole is used as a retaining member in Patent Document 3.